For detailed decription of problem see attachment.
Thank you for attached information.
As DARwIn OP has been released quite long ago, the battery on the SBC could be drained.
Although it has not proven that your issue is occurring because of the low battery, replacing the mainboard battery is a good start point to resolve the problem.
The development team also handed me the following link as a reference.
Please let us know if this bug is not relevant to your problem.
I had a similar message with darwin-op 1. I solved by :
On startup: access the bios, change the date and time by the current one and save it ; did it work with you ?
if i don't use it for a while (more than a week) i need to do it again. Like Will Son suggested it it's probably the battery on the SBC.